混合接种PN与PN/A颗粒污泥快速启动连续流自养生物脱氮反应器

Rapid Start-up of Continuous Autotrophic Nitrogen Removal Reactor by Hybridinoculating PN and PN/A Granular Sludges

在连续流条件下,快速培养亚硝化-厌氧氨氧化(PN/A)颗粒污泥是实现污水高效生物脱氮处理的关键技术.与PN/A污泥相比,亚硝化(PN)颗粒污泥具有生长周期短、易于批量化培养的优点,并可作为富集厌氧氨氧化菌(AMX)的载体.在3个完全混合流反应器(R1~R3)中,分别按照质量比3∶1、1∶1和1∶3混合接种PN/A和PN颗粒污泥,并通过设置高氨氮负荷、短水力停留时间和强水力剪切条件,成功启动了连续流自养生物脱氮工艺.结果表明,尽管R3的启动时长较R1和R2更长,但污泥接种比并未显著影响连续流反应器在稳定状态下的脱氮性能,总氮去除负荷均可达到2.6 kg·(m^(3)·d)-1以上.接种的PN颗粒污泥通过提供好氧氨氧化菌种(AOB),为AMX生长供给了充足的亚硝态氮基质,充分发挥了培养PN/A颗粒污泥的前驱体作用.由高通量测序结果可知,R1~R3中成熟颗粒的微生物丰度和多样性指数均明显高于接种污泥.AOB(Nitrosomonas属)和AMX(Candidatus Kuenenia和Brocadia属)与Chloroflexi、Bacteroidetes和Chlorobi等异养菌门是驱动自养生物脱氮和维持颗粒结构稳定的关键菌群.总之,PN与PN/A颗粒污泥的混合接种是快速启动连续流自养脱氮工艺的可行策略,对工程应用具有指导意义.

The rapid cultivation of partial nitritation/ANAMMOX(PN/A)granular sludge in a continuous-flow mode is one of the key technologies for efficient biological nitrogen removal in domestic wastewater treatment.Compared with that in PN/A granular sludge,PN granular sludge demonstrates a shorter incubation period and suitability for batch culture.It is also a good carrier for enriching ANAMMOX(AMX)bacteria.In this study,we established a continuous-flow autotrophic nitrogen removal process in three continuously stirred tank reactors(CSTR)(R1-R3)by hybrid-inoculating PN/A and PN granular sludge at the mass ratios of 3∶1,1∶1,and 1∶3,respectively.By implementing high ammonium nitrogen loading and short hydraulic retention time,continuous autotrophic nitrogen removal processes were successfully started up in the three CSTRs.The results showed that compared with that of R1 and R2,R3 had a longer start-up time but a similar steady-state nitrogen removal performance.The total nitrogen removal load of R3 could be more than 2.6 kg·(m^(3)·d)−1.Intriguingly,the inoculated PN granular sludge served as a precursor for PN/A granular sludge cultivation.This approach facilitated the enrichment of anaerobic ammonia-oxidizing bacteria(AMX)by introducing abundant ammonium-oxidizing bacteria(AOB)and nitrite nitrogen substrates into the CSTR.According to the results of highthroughput sequencing,the microbial abundance and diversity of the mature granules in R1-R3 were significantly higher than those of the inoculation sludge.AOB(genus Nitrosomonas),AMX(genera Candidatus Kuenenia and Candidatus Brocadia),and symbiotic heterotrophs,such as Chloroflexi,Bacteroidetes,and Chlorobi,drove the autotrophic nitrogen removal process and maintained the stability of the granular structure.In summary,a novel start-up strategy of hybrid-inoculating granular sludge was provided for a continuous-flow autotrophic nitrogen removal in engineering application.